In some electronic devices, including a smartphone, a tablet computer, and a laptop computer, it is not possible to use large speakers (such as those in dedicated, floor standing speaker cabinets) due to size and/or cost constraints. As these devices have become smaller in size with very limited space left for any individual component, the speakers have to be small as well. Therefore, small (micro) speakers having a diaphragm that is driven in the z-direction and whose largest dimension in the x-y plane is less than two inches for instance, are typically used for sound reproduction in these and most other small electronic devices. Nevertheless, it is also desirable to get high quality audio from these micro speakers, including a good bass response. However, small size and better audio quality are conflicting requirements, difficult and expensive to meet. It is a well-known characteristic of micro speakers to have poor low frequency response. For the speakers used in the devices mentioned above, the bass response is virtually nonexistent below 100 Hz. This frequency is even higher for even smaller devices such as smartwatches. As the human auditory system is logarithmic in nature, the low frequency (bass) range has a great impact on the overall quality of audio. Therefore, good bass reproduction is desirable.